In an unconsolidated undrained triaxial test, it is observed that an increase in cell pressure from $150$ kPa to $250$ kPa leads to a pore pressure increase $80$ kPa. It is further observed that, an increase of $50$ kPa in deviatoric stress results in an increase of $25$ kPa in the pore pressure. The value of $\textit{Skempton’s pore pressure parameter B}$ is

1. $0.5$
2. $0.625$
3. $0.8$
4. $1.0$